Born August 16, 1958, Madonna Louise Ciccone has come a long way since she first burst on the scene as pop music's "It Girl" of the early 1980s. Known by various names -- Madge, Esther, the Material Girl, and some unfit for a family news source -- Madonna is easily the top-selling female recording artists of all time and also the most controversial. A singer, songwriter, dancer, actress, activist, entrepreneur, and all-round entertainer, she's successfully reinvented herself throughout her career. She's often touted as both the Queen of Reinvention and the Queen of Pop, and it's clear she presides over both domains with confidence and clarity. It was convenient, if unintended, that her career flourished with the advent of MTV and that she took full advantage of the new medium to hew her image. She is, in every sense, the most media-savvy performer to come along in the past 50 years, Elvis and the Beatles notwithstanding.

Still, what's most impressive about Madonna -- beyond her outrageous stage antics, crazy costumes, outspoken opinions, African adoptions, and Kabbalistic tendencies -- is her ability to challenge herself and her audience by pushing the buttons and defying whatever norms and expectations society may harbor. She shows us what it feels like for a girl in a man's world.

Madonna has aroused the ire of critics, governments, MTV, the Catholic Church, big business, and practically every other entity with whom she might have otherwise courted favor. She is, in short, true only to herself and her art, making her the most uncompromising artist of the modern era. And that's why, even at age 54, every move Madonna makes attracts interest and attention from admirers and critics alike.

Still, despite her singular style, there are only a handful of other women who could be considered kindred spirits. And while the influence might not always be apparent, it's fair to consider them simpatico sisters.

Let's start by giving Cher her hurrahs for a career that eschewed compromise as part of her MO. While she started as a willing foil for her husband and musical partner Sonny Bono, her ability to forge solo stardom proved she had her own acumen when it came to reinvention. Her talent, tenacity, glitzy image, and ability to weld sexual suggestion have made her an outspoken icon unafraid to court controversy.

Like Cher, Tina Turner was also forced to fight her way out from under the control of a domineering mate. Hers abused and humiliated her while pursuing their stardom. Yet for all the success accorded Ike and Tina Turner, it was Tina's turn as a solo artist that truly elevated her into the stratosphere. Few stars have aged as gracefully; even well into her 60s, she struts suggestively with a sexuality that puts her younger contemporaries to shame. And damn if she doesn't possess the greatest pair of legs ever to grace a concert stage.

Bette Midler began her career entertaining the clientele of New York's bath houses, often accompanying Barry Manilow, who, at the time, was similarly employed. Even so, it was apparent early on that she was not only a sassy spitfire but a damned talented actress and interpreter as well. Packing personality plus, the Divine Miss M demonstrates that her show-biz moniker fits her in every way.

Like these other ladies, Annie Lennox made her mark singing alongside a male partner (Dave Stewart) with whom she collaborated in the Eurythmics. And while her vocal approach remains as emphatic as ever, being out on her own has allowed her to nurture her own idiosyncrasies. Her stage garb and cropped hair make an indelible impression, and her tendency to occasionally dress in drag puts her in the same quirky company as her aforementioned contemporaries.

Janet Jackson also knows how to exploit her sexuality, and she doesn't even dress in drag in to do so. But being a Jackson brings the weight of the media spotlight and the glare of some harsh publicity. Credit her with making the term "wardrobe malfunction" a part of our everyday vocabulary.

If anyone could be counted as genuine a Madonna makeover, Lady Gaga would get that nod. Ms. Gaga's admitted as much, citing Madge as her overwhelming inspiration. Still, relations between the Material Girl and the once-gushing Gaga have soured somewhat, given that Madonna slyly noted the unerring similarity between her own song "Express Yourself" and Gaga's "Born This Way." Madonna has labeled the tune "reductive" and on her current tour she interjects the chorus of "Born This Way" with "Express Yourself" to tout the similarities. Madonna's also nudged Gaga about her weight issues, prompting Elton John to jump into the fray in order to chastise Ms. Ciccone for her critical commentary. Can you say "Meoooooooooooooooow!"?

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